The present invention relates to the field of filling containers with a flowing product in a filling installation comprising a product reservoir and a filling unit enabling several containers to be filled simultaneously.
The problem underlying the technique of filling containers is to deliver a predetermined quantity (by volume, by weight, . . . ) of flowing product to each container within the shortest time (in other words, at the highest filling rate or at the highest flow rate) and to do so regardless of the actual capacity of the container and/or its geometric and dimensional characteristics and/or the rheological characteristics of the product being packaged.
These requirements give rise to a number of difficulties, particularly in installations where moving containers are filled continuously one after the other (in-line filling systems).
A first difficulty relates to the need to regulate rapidly and finely the flow rate supplied by each filling nozzle: it is, of course, possible to intervene manually in a filling plant under normal conditions but this has to be ruled out in certain types of installation (filling installations in a sterile environment in which any manual intervention would require the system to be shut down and a full decontamination cycle run before starting the system up again).
Another difficulty resides in the high loss of pressure which varies depending on the number of filling nozzles in operation at any one time (the nozzles are in principle supplied by force of gravity from a tank with a constant level). In particular, these pressure losses vary during phases when the installation is being started up or shut down as and when filling nozzles come into service, generally accompanied by variations in the flow rates at nozzles already in operation.
Furthermore, if an installation is operating continuously, an incident may occur in supplying one or more containers (a container is missing or incorrectly positioned underneath the nozzle). Depending on the technological layout of the installation, either the corresponding nozzle delivers the product, which is then lost (product wastage) or the nozzle is suppressed which modifies the flow rate of the other nozzles.
There is currently a demand for a remotely operated method (i.e. without manual intervention in the system) of positively and instantaneously controlling the effective individual flow rates of all the filling nozzles in the plant and such a control system needs to be easy to operate, as inexpensive as possible and undemanding in terms of maintenance.
To these ends, one of the first aspects proposed by the invention is a method of controlling the filling of containers with a flowing product within a filling system comprising a product reservoir and a filling unit, enabling several containers to be filled simultaneously, said method, configured as proposed by the invention, being characterised in that: the total real flow rate of the product delivered by
the filling unit to all the containers is measured, the theoretical number n of containers being filled within the filling unit is detected,
a theoretical individual filling rate of the containers q is displayed,
the measured total real flow rate and the theoretical flow rate nxc2x7q are compared and
if necessary, the real total flow rate is corrected to bring it into line with the theoretical flow rate, as a result of which, operation of the filling installation can be adapted to the number of containers being filled simultaneously without any significant variations in the real individual filling rates.
Implementing the method enables the desired requirements to be met, since the flow rates are managed fully automatically and no manual intervention is required in the installation: application of this method would be of particular interest for filling installations in a sterile environment.
Furthermore, regulation can be operated very quickly and the skilled person in particular would have no difficulty in setting up electronic means to work in real time. As a result, it would be perfectly feasible to apply the method proposed by the invention to an in-line filling installation, even if operated at a high rate, in order to manage the process of filling individual containers at an optimum flow rate, including transition phases (start-up, shut-down) of the installation and during continuous operation, in particular to deal with any faults in the supply to the containers (container missing or incorrectly positioned underneath (the-nozzle).
As a second aspect, the invention proposes an installation for filling containers with a flowing product, comprising a product reservoir and a filling unit fitted with a plurality of filling nozzles enabling several containers to be filled simultaneously, said installation, configured as proposed by the invention, being characterised in that it comprises:
a proportionally controllable valve, incorporated in the supply line between the filling unit and the product reservoir,
means for measuring the total real flow rate of the product effectively circulating in the filling unit,
sensor means designed to determine the number n of containers being filled within the filling unit,
means for displaying the theoretic individual filling rate q of the containers,
computing means for determining the global theoretical flow rate nxc2x7q of the product to be supplied to the filling unit, and
comparator means receiving and comparing the data pertaining to the total real flow rate measured by the measuring means and the theoretical flow rate computed by the computing means, said comparator means having a control output connected to a control for the valve regulating the product flow supplied to the filling unit.
Throughout the description, any valve which can be regulated on a proportional basis will be referred to as a proportional valve.
In one possible embodiment, the means for measuring the total real flow rate of the product comprise a flow meter for measuring relatively high flow rates, disposed in series with the main proportional valve and, for measuring relatively low flow rates, a circuit bypassing the main proportional valve having a flow meter for measuring low flow rates and a secondary proportional valve, the main valve and the secondary valve being selectively brought into service depending on the flow rate to be measured.
In another possible embodiment, the means for measuring the real flow rate of the product comprise a plurality of individual flow meters co-operating respectively with the filling nozzles and summing means to determine the sum xcexa3qi of the individual flow rates qi detected.
The means proposed by the invention are preferably applied in an installation in which the filling unit is set up as a rotating carousel with filling nozzles distributed around the periphery, the containers being filled on a predetermined angular sector of the circular path followed by the nozzles, and more specifically may be applied in such an installation designed to fill containers in a sterile environment.